Modern habitability and the possibility of extant life on Mars
Pascale Ehrenfreund1,2
1Space Policy Institute, Washington DC, USA 2Leiden Institute of Chemistry, NL Origin of Life
Abiotic synthetic reactions Organics from space on the early Earth
Prebiotic soup
The origin of life First evidence for Origin of Life on Earth ….. life ~ 3.5 billion years ago; prokaryotic, anaerobic, Life needs …. heterotrophic ?
• Water • Energy • Organic molecules
Information mechanism Bacteria rule the Earth
Credit: Tullis Onstott 5 x 1030 ? 92 % of bacteria live underground Bacteria produce oxygen, fix nitrogen, they decay as pollutants and dissolve rocks …. 4000 species in a gram of soil Extreme Life …. Hydrothermal vents
Antarctica
Nymph Greek Iron Spring
Cyanidium caldarium at pH~3.3 und 42 C
Norris Geyser Basin, Yellowstone Park PotentialPotential sources sources of organic matter of on organics Mars on Mars
The direct synthesis of organic compounds and/or the development of life may have taken place on Mars early in its history …
Meteoritic infall should have delivered organic compounds to Mars at a rate of
2.4 x 106 kg yr-1 or ~ 0.1 nm Abiogenic synthesis coverage per year (Zent 1994, Flynn 1996)
CO2 /H2O/C x Hy + energy organics
LOCALIZED AND LOW BIOMASS Exogenous infall Martian conditions
15 -1 -2 UV flux (190-325 nm) Flux: ~1.4 × 10 photons s cm -2 Intensity: ~37 W m Ionizing radiation Dose: ~ 0.2 Gy/year
Atmospheric composition 95.3% CO2 ; 2.7% N2 ;
1.6% Ar; 0.13% O2; 0.03% H2O, CH4 ? photochemically produced transient species
Surface temperature 140 to 300 K; average: 210 K
Oxidants H2 O2 ; -Fe2 O3 ; dry acids from SO3 ;
perchlorates ; O3 , O2 , O …
Dust/atmospheric pressure Plasma exposure, winds; 7mbar
Extant life may be present in ecological niches and in the subsurface SearchingSearching for for life onextant Mars ….. life on Mars …
Growing life Dormant life Geochemical tracers
MEPAG Goal 1: Objective B (2010)
Evidence of ongoing metabolism/chemical gradients
Characterize organic chemistry and bioessential elements
Seek evidence of organic and mineral structure that may be associated with life Martian habitats
Caves: Pit craters in Tharsis region may host cave entrances (Cushing 2011); access to minerals, gases, ices, and any subterranean life: ACCESS Mars (ISU 2009)
Hydrothermal vents: Deposits of pure silica identified; (geologic activity and water/ice); on Earth hydrothermal deposits team with life
Subsurface: Life has been detected a few km below Earth’s surface; bacteria, recently nematodes in 1.3 km depth (Halicephalobus mephisto)
Subsurface ice: Polar regions, northern plains, impact basins and rims etc.; microbes may be preserved Gaetan Borgonie Martian habitats
Evaporite deposits: Upwelling groundwater is responsible for the abundant evaporite deposits; Terra Sirenum chloride salt deposits similar to Atacama Desert salt deposits
Antarctic-like paleosols: Microbial life in paleosols with minor amounts of Fe available, argues for potential of microbial life
Surface rocks: Clay-carbonate rocks Nili Fossae identified (CRISM/HiRISE) that date back to the Noachian period – conditions in the region could have been suitable for life (analog to Pilbara, Australia) Defining extant life environments on Mars
Imaging of Mars habitable regions Earth analogue field research in extreme environments Laboratory simulations of biota and biomarkers under Mars condition: radiation, temperature, oxidation, racemization… Experiments in Low Earth Orbit (ISS and small platforms) Supporting surface chemistry and theoretical modelling
Optimize payload performance for missions in development Optimize extraction procedures, sample handling, sample processing and planetary protection Optimize geo-context for biomarker measurements, concerning deposition history, diagenesis and instrument performance Adapt extant life search strategies to landing site constraints Na+ 163 JPL/Ames/Leiden crew in the - NO3 64 Atacama Desert - Peru 2005 pH 4 AA 1000 ppb
Peeters et al. 2009
Na+ 6780 - NO3 5270 Low abundance of organic material - strong pH 7 diversity in composition within areas of several m AA 50 ppb JPL/NASA Ames/Berkeley/Leiden Jarosite
UREY Field test Panoche Valley May 2004
Skelley et al. 2005
Complete sample-to-result field analysis
Amino acids in jarosite Detection 50 pptr to 100ppb level First time on-site DNA analysis by PCR at MDRS March 2009 Total number of samples positive for bacterial, fungal and/or archaeal DNA
Thiel et al. 2011 Life and Amino Acids in dry deserts….
Atacama: Biomass 8.5x106 – 6x107 cells/g (PLFA) 6.3x102-5.2x103 CFU/g 600 ppm TOC (Lester et al. 2007)
Amino Atacama Atacama Utah Utah Utah Acid (ppb) Peru Yungai Morrison Mancos Dakota Glycine 91 102 92 1324 17390 L-Alanine 283 92 76 1114 32934 L-Glutamic 62 116 194 600 10892 Acid L-Aspartic 35 57 102 220 7775 Acid Peeters et al. 2009, Martins et al. 2011 Mars simulations
How do microbes thrive in a desiccated, cold, salty, hypobaric martian environment and how do they cope with soil oxidation and ionizing radiation ?
Worldwide activities: many species have been tested to survive one or several environmental conditions such as desiccation and UV radiation, low temperature etc. There are no simulations that are able to test for all parameters simultaneously !
Examples: Halobacterium salinarum NRC-1, Halorubrum chaoviator, Chroococcidiopsis sp. 029, Bacillus pumilus, Psychrobacter Cryohalolentis, homogenized bacterial permafrost community, E.coli ….. (Mancinelli et al. 2004, Cockell et al. 2005, Schuerger et al. 2006, Beaty et al. (2006), Osman et al. 2007, Peeters et al. 2009, Smith et al. 2009, Hansen et al. 2009, Berry et al. 2010)…… Low pressure growth limit
Growth of Bacillus subtilis cells was progressively inhibited by lowering of pressure and ceased at 2.5 kPa (Nicholson et al. 2010)
Hypobaria likely species specific; no bacteria has shown replication below 25 mbar, most resistant is Serratia liquefaciens (Schuerger et al. 2011)
Active metabolism (methanogenesis) at 400 and 50 mbar of Methanothermobacter wolfeii, Methanosarcina barkeri and Methanobacterium formicicum on JSC-1 analog (Kral et al. 2011)
Strong link to Planetary Protection Adaptation for enhanced growth at low pressures possible… ? Punctuated equilibrium ? (Gould 2007) Space Exposure Facilities Long Duration Exposure Facility (LDEF), ERA/EURECA, BIOPAN/FOTON, EXPOSE-E and EXPOSE-R
Extended space exposure allows us to collect data on multiple samples Recent Biopan Results
BIOPAN 5/6:
ORGANICS: Investigations of large organic molecules, such as polycyclic aromatic hydrocarbons (PAHs): Minimal destruction (Ehrenfreund et al. 2007)
UVOLUTION: Investigation of half-lives of several amino acids, urea and HCN polymers and the stability of carboxylic acids and carbonates on simulated martian surface: Results differed from ground truth (Guan et al. 2010, Stalport et al. 2010a,b)
MARSTOX: Investigation of protective and/or toxic effects of Mars regolith simulant on bacterial spores in outer space or simulated Mars environment: High lethality of solar extraterrestrial UV radiation (Rettberg et al. 2004)
LICHENS: Experimental test of Lithopanspermia hypothesis with lichens on natural rock habitat: High survival (Sancho et al. 2007, De la Torre et al. 2010)
TARDIS: Tardigrades survive exposure to space in LEO (Jönsson et al. 2008) O/OREOS (Organism/Organics Exposure to Orbital Stresses) Dual payload: Monitor how exposure to space radiation and weightlessness changes biology and organic molecules
Goal 1: Measure the survival, growth and metabolism of two different microorganisms using in-situ colorimetry
Goal 2: Measure the changes induced in organic molecules and biomarkers using ultraviolet and visible spectroscopy MOMA: Mars Organic Molecule Analyzer
MOMA is a joint European and US instrument that combines gas chromatography and laser desorption to an ion trap mass spectrometer.
GC-MS: detection of volatile molecules (atmosphere/sediments) LDMS: detection of less volatile molecules Exomars 2018
Optical Fiber
Laser Head
Tapping station Electronic Box Life Marker Chip
Fig 5b. Example fluorescent LMC microarray assay for benzo[a]pyrene (B[a]P); 1.6 x 1.6 mm2, 25 spot homogeneous arrays – used in development – Antibody micro-array technology varying intensity between arrays due to detection of different concentration of B[a]P
Antibodies immobilized to a surface act as Exomars 2018 receptors to capture specific organics
Extinct Life – preservation / diagenetic products of ancient life (geo-molecules)
Extant Life – short lived products of present life (bio-molecules)
Abiotic organics – examples of meteoritic in-fall, preservation / diagenetic product Fig 4b. Design early June 2011 of early Mars organics inventory Life Marker Chip Flight Model design (June 2011) List of possible LMC targets
Parnell et al. 2007 Expandable smectite minerals Clay mineral group- interlayer spacing (001) expands with the absorption of water or organic molecules between the 001 layers
Montmorillonite Nontronite
[001]
(K,Na,Ca)0.3 (Al,Mg)2 Si4 O10 (OH)2 * nH2 O Na0.3 Fe2 (Si,Al)4 O10 (OH)2 * nH2 O
Monoclinic C 2/m Critical aspects and constraints for organic and life detection on Mars
Ehrenfreund et al. 2011 Recommendations
Search for extant life should be a targeted international effort
Optimize existing mission payloads for extant life search
Develop new mission concepts and instrument technology
Discovery-type missions, dedicated, focused, with specific instrumenation to identify extant life (Davila et al. 2010)
Create long-term program in synergy with Earth Science to exploit analogue sites in preparation for MSR